Rheem Error Codes & Diagnostic Codes

Updated October 13, 2026 · by Aurora Star Tech Inc.

Rheem error codes and diagnostic codes: look up a code to see what it means, the likely causes and the steps to fix it.

Rheem error codes by equipment type

Rheem Furnace error codes

Code	Meaning
1 blink	Soft lockout (failed ignition)
2 blinks	Pressure switch circuit open
3 blinks	Limit circuit open
4 blinks	Pressure switch circuit closed (stuck closed)
5 blinks	Twinning fault (optional)
6 blinks	Line and neutral reversed
10	One-hour lockout
11	Failed ignition
12	Low flame sense
13	Flame lost
14	Unexpected flame
20	Twinning fault
22	Main limit open
23	HALC limit open (HALC LIMIT OPEN)
26	Line and neutral reversed
33	Rollout switch (MRLC) open
44	Low pressure switch closed (stuck)
45	Low pressure switch open - inducer high speed
46	Low pressure switch open - inducer low speed
55	Pressure switch stuck closed
57	Pressure switch stuck open
58	Water sense circuit open
59	Water sensed / blocked drain
60	Blower fault - running (BLWR FLT-RUN)
61	Blower fault - blower not running
66	Blower overspeed (BLOWER OVRSPEED)
68	No blower communication (NO BLWR COMM)
82	Supply air sensor fault (SA SENSOR FLT)
93	Internal control fault
d1	No shared data (NO SHARED DATA)
d4	Memory card invalid (MEM CARD INVALD)
d5	Card/hardware conflict (CARD-HRD CNFLCT)
d6	Blower HP conflict (BLWR HP CNFLCT)
d7	Blower manufacturer conflict (BLWR MFG CNFLCT)
d8	Old shared data (OLD SHARED DATA)
Flame LED off	No flame sensed (troubleshooting aid)
Flame LED rapid blink	Amber flame LED - unexpected flame
Flame LED slow blink	Amber flame LED - marginal flame sense
h flashing	Calibrating (CALIBRATE-NO V)
r	Lockout indicator

Rheem Heat Pump error codes

Code	Meaning
01	Long run time (compressor)
1 flash (L terminal)	L-terminal fault output: Long run cycle or low pressure
02	High side fault (compressor limit opened 4 times)
2 flashes (L terminal)	L-terminal fault output: High pressure control trip
03	Short cycling
3 flashes (L terminal)	L-terminal fault output: Unit short cycling
4 flashes (L terminal)	L-terminal fault output: Locked rotor
05	Open circuit - compressor will not run
5 flashes (L terminal)	L-terminal fault output: Compressor will not run, open circuit
06	Compressor open start circuit
6 flashes (L terminal)	L-terminal fault output: Open start circuit
07	Compressor open run circuit
7 flashes (L terminal)	L-terminal fault output: Open run circuit
8 flashes (L terminal)	L-terminal fault output: Control mis-operation
09	Low secondary (control) voltage
9 flashes (L terminal)	L-terminal fault output: Low control voltage
21	Low pressure control (LPC) open
27	Low line voltage or no line voltage
28	High line voltage
29	High pressure control (HPC) open
30	ICC fuse open
80	Low airflow
83	Condenser coil temperature sensor fault
84	Outdoor ambient temperature sensor fault
90	Communication fault
93	Internal control fault
d1	No shared data
d3	Airflow CFM mismatch
d4	Memory card invalid for device
d8	Old shared data
Flashing c / C / h / H	Anti-short-cycle (3 min) or minimum-run (30 s) timer active
L4	Locked rotor lockout
L6	Open start circuit lockout
L7	Open run circuit lockout
L21	Low pressure control lockout
L29	High pressure control lockout
P	Compressor protector trip

Find codes by Rheem model

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.

Rheem error codes by equipment type

Rheem Furnace error codes

Rheem Heat Pump error codes

Find codes by Rheem model

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